Waveguide fitting for coupling helical elliptical waveguide



G. HIRSCH ETAL 3,300,741

WAVEGUIDE FITTING FOR COUPLING HELIGAL ELLIPTICAL WAVEGUIDE Jan, 24, 1967 Filed May 12, 1965 Fig. 7

17 ford mac/1 mm? United States Patent 3,300,741 WAVEGUIDE FITTING FOR COUPLING HELICAL ELLIPTICAL WAVEGUIDE Gerhard Hirsch and Wolfgang Krank, Backnang, Germany, assignors to T elefunken Patentverwertungsgesellschaft m.b.H., Ulm, Danube, Germany Filed May 12, 1965, Ser. No. 455,155 Claims priority, application Germany, May 12, 1964, T 26,168 9 Claims. (Cl. 333-98) The present invention relates generally to the microwave art, and, more particularly, to a fitting for' very high power waveguides, wherein a corrugated-tube Waveguide is used having an elliptical or ellipse-like cross section, and wherein the waveguide is held by positive means and/or by its shape between two appropriately shaped half shells, and the flanged end of the waveguide is pressed against the end face of a plug member by a pressure edge of the half shell.

Waveguide fittings of this kind are known. One of the possible constructions is illustrated in FIGURE 1. The fitting is shown partially cut away so that the corrugated waveguide 1 can be seen. In the example illustrated, metal parts 4,'which are constructed in the form of half shells, serve to grip the waveguide. The parts 4 form a pressure edge 8 which is pressed against the flanged rim 2 of the waveguide 1 by means of a screw connection 9, so as to render possible the required mechanical connection between the corrugated waveguide and the plug member 3.

Waveguides of this kind are normally provided with a dielectric cover. A portion of this cover is visible in FIGURE 1 and is identified by the reference numeral 14. The plug member 3 is constructed in the form of a sleeve which renders possible the mechanical connection of the individual parts to form a unit. A rubber seal 11 is provided between the sleeve 17 of the plug member 3 and the end of the dielectric cover 14 which surrounds the waveguide 1. This rubber seal 11 is arranged between two metallic pressure discs and 13. The counter nut 12 which is screwed into the sleeve 17 provides the pressure for the sealing unit, which in addition affords support for the waveguide.

Since the corrugated waveguide has a helical corrugation, the pressure edge 8 of the half shells 4 at the circumference always lies outside the maximum major and the maximum minor axis, respectively, of the ellipse. The connector waveguide has such a cross section that the dimensions of the axes lie between the inside cross section of the corrugated waveguide and the inside cross section of the corrugated waveguide enlarged by the depth of the corrugations of the profile.

The part of FIGURE 1 which represents the contactmaking zone is shown on a larger scale in FIGURE 2. The pressure edge 8 obviously does not coincide with the dimensions of the waveguide 15 as a result of which there is an undefined contact between the parts 2 and 15 which leads when operating with pulses of about 3.10 watts or in continuous operating with 1,5 .10 watts to an unwanted peak effect for the field strength which occurs in the case of high power. The reference numerals for the individual parts in FIGURE 2 have been selected to correspond to the numerals in FIGURE 1.

With this in mind, it is the object of the present invention to provide a fitting in which such disadvantage is avoided.

Another object of the invention is to provide a waveguide arrangement of the character described wherein field strength peaks particularly at high power are avoided.

These objects and others ancillary thereto are accom- 3,300,741 Patented Jan. 24, 1967 plished in accordance with preferred embodiments of the invention wherein a corrugated waveguide with an elliptical or ellipse-like cross section is provided. The waveguide is held by positive means and/or by its shape between two appropriately shaped half shells and the flanged end of the waveguide is pressed against the end face of a plug member by a pressure edge on the half shell. The plug member is provided at the surface against which the flanged collar of the corrugated waveguide bears, with such a recess that the effective waveguide cross section is enlarged in the region of the maximum longitudinal currents in the waveguide wall.

Additional objects and advantages of the present invention will become apparent upon consideration of the following description when taken in conjunction with the accompanying drawings in which:

FIGURE 1 is a partial longitudinal sectional view of a known type of fitting.

FIGURE 2 is an enlarged fragmentary sectional view showing the contact pressure point of FIGURE *1.

FIGURE 3 is a fragmentary sectional view similar to FIGURE 2 but illustrating the present invention.

FIGURE 4 is a diagrammatic end view of the present invention.

FIGURE 3 shows a part of the waveguide fitting of FIGURE 1, constructed according to the invention and shown on a larger scale. The corrugated waveguide 1 is flanged at its end 2 and lies with the flange collar between the plug member 3 and the two half shells 4 provided with a pressure edge 8. In order to ensure a definite electrical contact and so to prevent at the same time a flash-over when using high power, the plug member 3 is provided with a certain recess 5 at the surface against which the flanged collar 2 of the waveguide 1 bears.

FIGURE 4 illustrates diagrammatically the shape of the above-mentioned recess 5. The circle 16 represents the outside diameter of the sleeve 17. The curve 7 in chain line represents the line along which the pressure edges 8 of the half shells 4 press against the flanged collar 2 of the corrugated waveguide 1. The recess 5, which is substantially circular, is situated at the point where the maximum longitudinal currents occur at the waveguide wall, that is to say, substantially in the middle of the two wide sides of the waveguide. The longitudinal extent 2 of the recess 5 in the direction of the major axis of the waveguide is preferably selected between 0.2a and 0.4a when a designates the major inside axis of the waveguide, the minor internal axis of which is b. The recess is preferably made circular, the diameter of the circle 6 being equal to the minor axis of the course 7 of the pressure edge. The depth t of the recess 5 is less than A 10, in which A designates the waveguide wavelength.

For waveguides in which the ratio of the axes b/a is small, on the other hand, the recess may be constructed in such a manner that it coincides with the course of the pressure edge 8 over as great a distance as possible. The recess 5 would be constructed in a similar manner if the following waveguide 15 has a rectangular or similar cross section.

It will be understood that the above description of the present invention is susceptible to various modifications, changes and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.

What is claimed is:

1. In a waveguide fitting for very high power, wherein a corrugated waveguide having an elliptical or ellipselike cross-section is used and wherein the waveguide is held by positive means and/ or by its shape between two appropriately shaped half shells and the flanged end of the waveguide is pressed against the end face of a plug section by a pressure edge on the half shell, the improvement wherein the plug section is provided, at the face against which the flanged end of the waveguide bears, with such a recess that the effective waveguide crosssection is enlarged in the region of the maximum longitudinal currents in the wall of the waveguide.

2. A waveguide device, comprising, in combination: a corrugated waveguide having and elliptical-like crosssection and a flanged end; a pair of half shells firmly holding the waveguide and having a pressure edge; and a plug section having an end face against which the flanged end is pressed by said pressure edge, said plug section having a recess in said face which provides that the effective waveguide cross-section is enla-rged in the region of maximum longitudinal currents in the wall of the waveguide. 3. A wavelength device, comprising, in combination: a corrugated waveguide having an elliptical-like crosssection and a flanged end; a pair of half shells firmly holding the waveguide and having a pressure exerting edge; and a plug section having the interior of the waveguide and an opening therethrough aligned with an end face against which the flanged end is pressed by said pressure edge, said plug section having a recess in said face which provides that the eflective waveguide cross-section is enlarged in the region of maximum longitudinal currents in the wall of the waveguide.

4. A device as defined in claim 3 wherein starting from the end points of the minor axis of the waveguide the recess decreases gradually toward the major axis.

5. A device as defined in claim 4 wherein said recess is substantially circular and the diameter of the recess corresponds to the minor axis of the cross-section of the pressure edge.

6. A device as defined in claim 4 whereiin the length of the recess in the direction of the major axis a of the waveguide cross-section is between 0.2a and 0.4a.

7. A device as defined in claim 4 wherein the depth of the recess is less than 10 where A is the wavelength of the waveguide.

8. A device as defined in claim 3 wherein the recess has such a shape that the pressure edge coincides with the edge of the recess over as great a distance as possible.

9. A device as defined in claim 3 comprising a further waveguide connected to said plug and having a crosssection which is different from the effective cross-section of the corrugated waveguide.

No references cited.

HERMAN KARL SAALBACH, Primary Examiner.

L. ALLAHUT, Assistant Examiner. 

1. IN A WAVEGUIDE FITTING FOR VERY HIGH POWER, WHEREIN A CORRUGATED WAVEGUIDE HAVING AN ELLIPTICAL OR ELLIPSELIKE CROSS-SECTION IS USED AND WHEREIN THE WAVEGUIDE IS HELD BY POSITIVE MEANS AND/OR BY ITS SHAPE BETWEEN TWO APPROPRIATELY SHAPED HALF SHELLS AND THE FLANGED END OF THE WAVEGUIDE IS PRESSED AGAINST THE END FACE OF A PLUG SECTION BY A PRESSURE EDGE ON THE HALF SHELL, THE IMPROVEMENT WHEREIN THE PLUG SECTION IS PROVIDED, AT THE FACE AGAINST WHICH THE FLANGED END OF THE WAVEGUIDE BEARS, WITH SUCH A RECESS THAT THE EFFECTIVE WAVEGUIDE CROSSSECTION IS ENLARGED IN THE REGION OF THE MAXIMUM LONGITUDINAL CURRENTS IN THE WALL OF THE WAVEGUIDE. 